Reference Unit - TX
Reference Unit specifies the basis or denominator for which a declared environmental impact or quantitative value is expressed. It answers the question: “Per what amount of product, material, or function is this value valid?”
Reference Units allow for contextualizing environmental impact data such as carbon footprint or water use. They ensure that values are comparable and meaningful within and across products, categories, and use scenarios.
Purpose
The Reference Unit defines *what the value is expressed per* and is a core component of standardized environmental declarations. It is distinct from the Value Unit, which expresses *what the value is measured in*.
Common Reference Units
| Reference Unit | Key | Description |
|---|---|---|
| Kilogram | kg | Value is expressed per 1 kg of product or material. |
| Liter | L | Value is expressed per 1 liter of product (common for liquids). |
| Functional Unit | FU | A defined reference scenario for use (e.g., one wash, 1000 hours of use). |
| Sales Unit | SU | The actual product unit as sold (e.g., a single package, bottle, or device). |
Functional Unit Detail (Optional Layer)
If the Reference Unit is set to FU (Functional Unit), an additional data can be provided:
- FU Key: A standardized code or string representing the functional unit,optional if standardized, example is "DFU", for Daily Food Unit
- FU Description: A localized, human-readable explanation, example
- English (eng): A wash cycle of 5 kg of cotton at 40°C
- Dutch (dut): Een wasbeurt van 5kg katoen op 40°C
This structure supports multilingual declarations and precise LCA communication.
Use in IMDE
In the IMDE model, each environmental declaration includes:
- The Value Unit — e.g., `kg CO₂eq`
- The Reference Unit — e.g., `per kg`, `per FU`, `per SU`
- Optional: FU Key and Description for functional units
This modular structure enables flexible data modeling across industries and life cycle stages.
Examples
- Climate Change: 0.85 kg CO₂eq per kg of detergent
- Water Use: 12.3 m³ per FU, where FU = 1 wash cycle (see FU key/description)
- Energy Use: 1.1 MJ per SU, where SU = 1 LED bulb (retail package)
